Will Aluminium be hard enough?

[DannyC]

I need to make a threaded insert that goes into the threaded sleeve of a freewheel (c.34mm Dia).
Options are to make this out of Mild steel or Aluminium. Aluminium will be a lot lighter.
In the centre of this piece a 12mm AF hexagonal hole must be broached.

Will aluminium be hard enough to cope with a steel hex in the hex hole keyway do we think?
The part with the hole in will be about 15..20mm thick, so it isn't like it is a 1mm plate with a hexagonal hole (which would be torn to bits in a short while I would think).

 

[undertoad]

At that diameter, aluminum would work, but those threads are mighty fine, so do a good job
Freewheel style aluminum wheel hubs are threaded for that every day.
Make sure it's at least 6061 - 7075 might be better, but of course, much more expensive.

 

[DannyC]

At that diameter, aluminum would work, but those threads are mighty fine, so do a good job
Freewheel style aluminum wheel hubs are threaded for that every day.
Make sure it's at least 6061 - 7075 might be better, but of course, much more expensive.

What about 6082 is that too soft?

 

[undertoad]

I looked it up
6082 is actually stronger and harder than 6061, BUT, somewhat more difficult to machine - Always a catch.
Something about needing a different cutting lube?
You should research - If you can cut it, it'd probably work great.

 

[Popshot]

I'd expect that it'd work but it's lifespan would be unacceptable. Even in perfect alignment the drive / coast force changes would wear at it and the slightest misalignment would exacerbate that.

Didn't this start out as a build it from obtainable parts exercise?

 

[undertoad]

Can you drill and tap the part for some opposing set screws - That might lock it to the hex shaft, and keep it from fretting.
It would be like locking an aluminum pulley on a shaft, then.

 

[undertoad]

Didn't this start out as a build it from obtainable parts exercise?

Cascading technology strikes again ........

 

[DannyC]

I'd expect that it'd work but it's lifespan would be unacceptable. Even in perfect alignment the drive / coast force changes would wear at it and the slightest misalignment would exacerbate that.

Didn't this start out as a build it from obtainable parts exercise?

Yes, there are in fact 3 versions of the 2WD unit. One all from standard parts, and two others that include custom bits.
I can (of course) make the hex receiver out of mild steel, but I bet my very expensive (£50) broach bit would prefer to eat the softer Aluminium.
I think I will make it in 6068 Aluminium first off and tell them to check for wear, and then if it is getting chewed-up I can make one in steel to replace it. It will be a slip the half-shaft out, unscrew the fitting and screw the replacement in.